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The evaluation of the structural behaviour of iconic historic buildings represents one of the most current structural engineering research topics. However, despite the various research works carried out during recent decades, several issues still remain open. One of the most important aspects is related to the correct reconstruction of the complex geometries that characterise this type of construction and that influence structural behaviour, especially in the presence of the horizontal loads caused by seismic action. For these reasons, different techniques have been proposed based on the use of laser scanners, Unmanned Aerial Vehicles (UAVs), and terrestrial photogrammetry. At the same time, several analysis methods have been developed that include the use of linear and non-linear approaches. In this present paper, the seismic performance of the Santa Maria Novella basilica and Santa Maria di Collemaggio basilica (before the partial collapse due to the 2009 L’Aquila earthquake) were investigated in detail by means of several numerical analyses. In particular, a series of non-linear time history analyses (NTHAs) were carried out, as reported in the Italian Building Code. To represent the non-linear behaviour of the main structural elements, smeared cracking (CSC) constitutive law was adopted. The geometry of the structures was reconstructed from a complete laser scanner survey of the churches, in order to consider all the intrinsic irregularities that characterise the heritage buildings. Finally, a comparison between the structural behaviour of the two case studies was carried out, highlighting the differences and similar aspects, focusing on possible collapse mechanisms and the identification of the most critical structural elements represented, in both cases analysed, by the main pillars of the transept.

As a consequence of climate change impact, a significant variation in terms of temperature, atmospheric humidity, and carbon dioxide concentration levels is happening. This condition leads to several negative effects on the safety and the life cycle of existing concrete structures, such as the increase in the rate of material degradation, due to corrosion phenomena. In fact, the presence of carbonation and corrosion phenomena significantly influence the load-bearing capacity of existing reinforced concrete (RC) structures, under both static and dynamic loads. Among the wide range of existing RC constructions, bridges stand out for their importance. Furthermore, as structures directly exposed to the weather effects, they are more susceptible to these phenomena. In this paper, the influence of corrosion on existing RC motorway viaducts’ seismic behavior, considering the impact of climate change, is investigated, by means of an efficient procedure based on the implementation of 3D simplified finite element models and the use of analytical relations to obtain the amount of reduction in the steel reinforcement area as a function of the age of the bridge and of the different corrosion scenarios analyzed. Several scenarios for the expected variations in CO2 concentrations, temperature, and relative humidity are evaluated, considering that most of the viaducts present in the Italian motorway network were built between the 1960s and the 1970s. The results obtained using the projection of climate change impacts are compared with those calculated considering the corrosion scenarios resulting from the DuraCrete research project, to understand if the evolution of climate change leads to worse scenarios than those previously assessed.

The preservation and definition of the correct retrofitting interventions of historic masonry buildings represents a relevant topic nowadays, especially in a country characterized by high seismicity zones. Considering the Italian Cultural Heritage, most of these buildings are constructed in ancient unreinforced masonry (URM) and showed a high level of vulnerability during the recent 2009 (L’Aquila), 2012 (Emilia Romagna) and 2016 (Centro Italia) earthquakes. In this paper, the seismic assessment of an historic masonry building damaged during 2016 Centro Italia seismic event is presented considering different types of retrofitting interventions. Starting from the results obtained by the post-earthquake survey, different finite element models have been implemented to perform linear and non-linear analyses useful to understand the seismic behaviour of the building and to define the appropriate retrofitting interventions. In particular, reinforced plaster layer and cement-based grout injections have been applied in each masonry wall of the building in order to improve their horizontal load-bearing capacity, and an additional wall made with Poroton blocks and M10 cement mortar has been built adjacent to the central stairwell. In addition, in view of the need to replace the roof seriously damaged during the seismic event, a cross-laminated roof solution characterized by a thickness equal to 14 cm (composed by seven layers, each 2 cm thick) has been proposed. The results show that the proposed retrofitting interventions have led to a significant improvement in the seismic behaviour of the building.

Throughout the last few decades, the scientific community has paid great attention to the structural safety of historical masonry constructions, which have high vulnerability with respect to seismic activities. Masonry towers are very widespread in Italy and represent an important part of the built heritage to be preserved. Different numerical methods with different levels of refinement were developed in the literature to evaluate their seismic performance. The present study shows a practical application of the seismic vulnerability evaluation of a masonry tower using different approaches. The aim is to provide practical suggestions to engineers for the successful evaluation of the performance of masonry towers under seismic loads. An in situ survey was performed to characterize the geometry of the structure and its constitutive material. All the collected information was introduced in a building information model, later used to generate different finite element models for the structural analyses. The global capacity of the structure was evaluated using three different models with different levels of complexity: the first simplified model is made of beam elements with cross-sections discretized in fibers; the second model is made of shell elements and uses a concrete damage plasticity model to describe the nonlinear masonry behavior; the third model adopts solid elements with a concrete smeared crack constitutive law. A preliminary eigen-frequency analysis is performed on the shell model to obtain some basic information about the structural behavior. Nonlinear static analyses were carried out for each model to understand the response of the tower under seismic loads, highlighting the main differences between the approaches. The behavior factor was evaluated on the basis of the analyses results and compared with the ones suggested by the Italian building code. The results showed that the towers do not satisfy the seismic demand required by the standards for all the considered models. Furthermore, the behavior factor calculated according to the Italian design code is overestimated, while the one evaluated by the simplified model is underestimated due to the neglection of the shear behavior. From all the analyzed configurations, the shell model resulted as a good compromise between reliable results and computation efficiency.

The paper presents a proposed framework to optimize the tuned mass damper (TMD) design, useful for seismic improvement of slender masonry structures. A historical masonry chimney located in northern Italy was considered to illustrate the proposed TMD design procedure and to evaluate the seismic performance of the system. The optimization process was subdivided into two fundamental phases. In the first phase, the main TMD parameters were defined starting from the dynamic behavior of the chimney by finite element modeling (FEM). A series of linear time-history analyses were carried out to point out the structural improvements in terms of top displacement, base shear, and bending moment. In the second phase, masonry’s nonlinear behavior was considered, and a fiber model of the chimney was implemented. Pushover analyses were performed to obtain the capacity curve of the structure and to evaluate the performance of the TMD. The results of the linear and nonlinear analysis reveal the effectiveness of the proposed TMD design procedure for slender masonry structures.

Over the last few decades, the attention on the safety of existing reinforced concrete (RC) structures has significantly increased. RC bridges, in particular, are highly relevant for strategic importance. In the Italian context, several of these bridges were built around 1960, when engineering practice commonly ignored or underestimated the presence of seismic actions. Therefore, it is fundamental to quantify as accurately as possible their seismic safety level with state-of-the-art analysis techniques. In this paper, an efficient procedure based on the multi-modal pushover analysis approach is proposed for the risk evaluation of several bridges of the Italian highway network. This procedure, tailored for portfolio level assessment, takes into account the non-linear behavior and the complex dynamic response this type of structure with limited computational effort. Three fundamental aspects are defined for the structural modelling of bridges, i.e., materials’ constitutive law, finite element type and nonlinear hinge models. Flexural and shear nonlinearities of piers are included to account for ductile and brittle damage potential. The standardized procedure guarantees consistent comparisons among different bridges of the same network in the form of risk indexes.

The behavior of a very slender building is investigated under wind loads, to satisfy both strength and serviceability (comfort) design criteria. To evaluate the wind effects, wind tunnel testing and structural analysis were conducted, by two different procedures: (i) Pressure Integration Method (PIM), with finite element modeling, and (ii) High Frequency Force Balance (HFFB) technique. The results from both approaches are compared with those obtained from Eurocode 1 and the Italian design codes, emphasizing the need to further deepen the understanding of problems related to wind actions on such type of structure with high geometrical slenderness. In order to reduce wind induced effects, structural and damping solutions are proposed and discussed in a comparative study. These solutions include (1) height reduction, (2) steel belts, (3) tuned mass damper, (4) viscous dampers, and (5) orientation change. Each solution is studied in detail, along with its advantages and limitations, and the reductions in the design loads and structural displacements and acceleration are quantified. The study shows the potential of damping enhancement in the building to mitigate vibrations and reduce design loads and hence provide an optimal balance among resilience, serviceability, and sustainability requirements.

A novel class of structures is proposed to realize ultra-wide-band radiating elements for large arrays, providing dual polarization, beam scanning, and compact and inexpensive realization based on suitable rhombic arrangements of dipoles printed on low-cost layered substrates. In a first implementation, four rhombic shapes, orthogonally placed on the same layer, provide two orthogonal polarizations. In a second implementation, the two polarizations are excited by two rhombic shapes printed on two different layers in a stacked-patch-like arrangement. This latter structure leads to a better lateral shielding of the single radiating element, in order to reduce mutual interactions among adjacent elements in array environment. The behavioral features of these antennas have been tested with various parametric analyses. Practical aspects have been addressed such as the choice of appropriate feeding and of commercially available dielectric layers. The resulting antennas are matched at the input ports in an extremely wide range of frequencies (5–25 GHz), covering various microwave applications, such as aircraft surveillance, weather polarimetric radars, and control and communications systems. Good radiating features, in terms of pattern shape and gain, are observed in a large band of frequencies. The basic scanning performance of large and small array configurations is finally investigated.